The present invention concerns a push button switch assembly and particularly a switch assembly which provides an improved arrangement for permitting only one push button switch actuator to be activated at any time from a plurality of such switch actuators.
Switch assemblies of different types have been previously proposed which enable an operator to select only one switch actuator from a plurality of switch actuators to be activated. Typically, such switch assemblies are provided with a plurality of push button switch actuators that are movable between two positions and interconnected with each other in a manner for causing in response to any one switch actuator being moved to its activated position, a switch actuator previously in that activated position to be returned to its deactivated position.
The difficulty with the prior art arrangements in the relatively complex arrangement of springs, plates, or levers for interconnecting the respective push button switch actuators so that they operate in the desired manner. For example, in U.S. Pat. No. 3,854,018, a cross-curved contact strip interconnects the push button switch actuators. And in U.S. Pat. No. 2,622,160, springs and rigid levers are employed between switch actuators. Also, in U.S. Pat. No. 4,061,072 and U.S. Pat. No. 4,133,989 a plurality of pivotally mounted switch actuators, each including a compression spring and latch mechanism, are coupled together by a string or wire for causing upon depression of a key from its initial position, a previously depressed key to be returned to its initial position.
Due to the complexity of prior art switch assemblies, the quantity of push button switch actuators and the physical configuration of the switch actuators comprising a switch assembly have been limited.
In the present invention, a matrix or assembly of push button switch actuators are interconnected by means of a flexible, unstretchable, electrically non-conductive belt or loop of a specified length which allows only one switch actuator of the assembly to be in an operative or activated position at one time while a switch actuator previously activated is caused to return to its inoperative or deactivated position. The belt is dimensioned so that when any one push button switch actuator is activated, the belt yields in the direction of motion of that switch actuator while the belt tension increases elsewhere along the length of the belt thereby causing a previously activated switch actuator to return to its deactivated position.
In order to maintain a selected push button switch actuator in its activated position, the switch actuator shaft includes a detent for engaging a detent spring molded into the switch assembly cover. The force created by the belt is sufficient for causing the disengagement of the detent of an activated switch actuator from the spring when another push button switch actuator is activated. A relatively simple switch assembly is achieved by molding the detent spring into the switch assembly cover.
A principal object of this invention is, therefore, the provision of an improved push button switch assembly which permits only one switch actuator at a time selected from a plurality of switch actuators to be activated.
A further object of this invention is the provision of a flexible, unstretchable, electrically non-conductive belt of a specified length in combination with a plurality of switch actuators for permitting only one switch actuator at a time to be activated.
Another object of the invention is provision of a detent spring molded into the push button switch assembly cover for retaining a switch actuator in its activated position and for providing a relatively simple switch assembly.
Further and still other objects of the invention will become more clearly apparent when the following description is read in conjunction with the accompanying drawings.